Matcha basically means rubbed or ground green tea and is used traditionally in Japanese Tea Ceremony. Matcha green tea plants are grown shaded before harvesting resulting in slower growth, higher chlorophyll (the good green stuff that has detoxifying properties) and production of amino acids. After harvesting, the leaves are dried, graded, de-stemmed and de-veined. The leaves selected for matcha (tencha) is then ground to matcha. High quality matcha should appear greener, and also taste 'greener', sweeter and more intense in flavour.
Usually comes as a fine, ground powder.